The applicant is the owner of the Italian Patents Nos. 1299454 and 1306755, as well as of the corresponding Patent Application PCT/IT99/00101 filed on 11 Nov. 1999, entitled “Hull for shipping with a mono-three-catamaran architecture”. Both previous patents and patent application disclose a parallel side hull having a pair of wing-contour chines, the lower edge of each chine beginning at a cross section plane near the bow under the waterline. Forward the hull has a central keel extending for a length less than the distance between the bow cross section and the midship cross section. The bottom of the hull between said chines, and between each chine and said central keel, where the keel is present, has convex bottom structures defining inverted longitudinal channels.
An object of the above mentioned hull is to convey the bow wave system into the bottom thereof and then to recover a portion of the energy spent in the wave system formation in order to increase the hydrodynamic sustentation of the hull.
However, this object is achieved only when the speed of the ship is very low, e.g. in barges or similar ships. When the speed increases, the angle formed by the bow wave system is reduced with respect to the situation in which the forward motion speed is low. With a high speed, the very forwarded chines are useless in conveying that wave system. Further, in the hull according to the previous applicant's patents the beam cross section is too great and positioned too forward with respect to the length of the ship. If one considers this fact together with the high extension of the chines which are fully submerged nearly to the bow, he comprises that the wetted surface is large, and as a result the resistance to forward motion is high.
Another drawback of the prior art, which is connected to the high extension of the fully submerged chines, is in general a highly difficult manoeuvrability of the ship.
Further, in the applicant's mono-three-catamaran hull, an increase of the speed would cause an excessive hydrodynamic thrust onto the bow. Such an excessive thrust would not be sufficiently counterbalanced aft by a pressure in said channel acting as a nozzle, even if this pressure is increased by enlarging the channel between the spaced apart chines and raising the bottom to the stern. Thus, the trim of the ship would not be kept constant, as, on the contrary, it is made provision by another object of the patents and patent application above cited.
Furthermore, another previous drawback is a poor ability of a hull to correct automatically its list as the mono-three-catamaran architecture acts as a supported beam without an accentuated righting moment.
Therefore, an object of the present invention is to overcome the above mentioned drawbacks which are met above all when the speed of a ship increases.
An object of the present invention is to provide a hull adapted to ships having a speed greater than that one allowed by the above mentioned hull.
An object of the invention is to provide a hull having an architecture with reduced resistance to the forward motion.
Another object of the invention is to provide a hull without a change in trimming at the cruising speeds.
Further, an object of the invention is to provide a hull having such a slender construction to be readily manoeuvred.
Furthermore, an object of the invention is to provide a hull having an improved ability to correct automatically its list.